2016/03/18

IR illumination and mortars

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I noticed that some things are simply passing under the radar, for they aren't 'sexy' enough and don't find multipliers who disseminate the information. Even people with great attention to military affairs, including insiders, often don't know about developments 10-30 years old even if those were not kept secret. This is particularly common regarding electronic warfare and surveillance technologies, but it afflicts even seemingly simple things such as mortars.

Here's one snippet that may close one such gap. Infrared illumination by mortar bombs and howitzer shells. The first generation of low light sensors depended on illumination searchlights. Some of the earliest examples are presented >>here<<.

Such illumination searchlights were still in use during the 1970's, particularly on tanks as gunner and driver aids at night. These devices work in the near infrared spectrum usually. Entirely passive devices that show the warmth of objects (and are useful even in daylight to find otherwise camouflaged vehicles and troops with ease) have become common in Western armies during the 1980's only, and for dismounted personnel during the 1990's. They're still rather expensive and rare as night sights for individuals as of today.

Instead, the typical rifle or helmet mounted night sight is a low light amplifying sensor that is sensitive enough to make do without an artificial illumination source usually. This misled many people to believe these would work well without any illumination, but they don't. They were called "starlight scopes" for a reason; at new moon or under dense clouds, far from civilian light sources and fires you won't see far with these. The availability of light sources coins the effective range.

The use of conventional illumination munitions is troublesome because these light amplifiers must not be pointed at an intense source of light (or be activated at daylight). The answer was to develop illumination munitions that are the typical flares on a parachute as known since the 18th century, but emitting light almost exclusively in the near infrared spectrum.

The slides below are excerpts from a presentation given in 2001 and show this technology:

So in other words; there's some need for illumination munitions even in the age of night sights (in addition to batteries for the latter).

I included the third page for a simple reason: I did write a couple times about how infantry needs to be elusive, to not stay for long in some place once detected. My rule of thumb was to not stay in a detected position for longer than two minutes.

The slide shows why; the potential for responsiveness is mortar (or artillery) fires within less than one minute. There are other lags in addition to this one, thus my rule of thumb of two minutes.

Please, form your own opinion on whether doctrines and equipment have evolved during the last 15 years in order to enable Western infantry to strike and vanish within two minutes routinely. Keep in mind how very much the attention was focused on occupation warfare where the opposing forces were devoid of even 1939-style mortar capabilities!

8 comments:

Near-infrared does not have much to do with the warmth of objects, unless they objects are quite hot. Warm objects show up in thermal infrared images (much closer to far-infrared)

Next, any flare putting out near-infrared will also put out quite a bit of visible light.

Standard illumination rounds are not that bright, especially at ranges one likes to be between you and the enemy. Don't point the sensor directly at the flare, point the sensor where you think the enemy is. If the flare gets between you and the enemy, move the next flare over a few hundred metres.

I changed the contradictory part to make sure it's clear IR flares also emit a bit visible light. The embedded PDF actually showed this anyway.

The vast majority of flares used are actually launched by signal pistols or 40 mm grenade launchers. Mortars and arty fire relatiely few illumination rounds by comparison. A problem with the easily man-portable flare launchers is the poor range, small illuminated area (due to small height) and short duration, of course. The range restriction of such munitions makes shifting flares to other places difficult. Mortars and arty can do, but with a longer lag. Furtermore, flares are hardly ever used continually; a poorly placed flare will often not be followed-on by another one for minutes if not hours.

I was convinced that ‘The use of conventional illumination munitions’ was unable to nullify a huge part of the IR… FLIR. I remember a Bofors’ advertisement from the 1990s ‘if they need light, just light them up’ or smthg like that: with a picture of an illumination shell in the skies. ‘If the room is dark and I cannot see, but someone else can see me; then I have a huge problem!’. ‘If I turn the light on, then we can see each other’. What if I can turn both, daylight and nightlight (IR,…FLIR) off; and let the other rascasse think it is walking around freely like a liberator of this Homeland? When, do you think KIKI, will it notice that we can see it, but it cannot see us?

I think that there are many parts needed to allow an effective routine of strike and vanish, and only the strike part is "clear":

It can begin with illuminating rounds (if poor visibility) but it should end with a rain of HE ammunition (one with very loud explosions and with a lot of smoke) --> attacked enemy will be disorganized and must remain in this state for some time, allowing own troops to "vanish".

About the "vanish" part... I think that you are right: it seems that no equipment has been developed for this. But I also think that this is a very difficult task: for me this could be ideally accomplished with soldiers moving like grasshopers... but that is not going to happen (at least in near future). So I can only think in some class of light vehicle (but I can't choose between bikes, motorcycles, perhaps an off-road version of http://www.jebiga.com/electric-three-wheel-motorcycle-sway/ , or whatever ) to improve infantry movement... but this seems easier to write than to do. Probably the design of successful UGVs will lead to the design of "the light vehicle the infantry needs".

I have heard claims that thermal imagers can spot a tank from 8 km away at night, and 6 km away at daytime. Do you think these distances are plausible, and if so, what kind of concealment is possible against them? You've said that well camouflaged soldiers should be unseen at distances of 100+ meters, so what range do you think a tank should be undetectable at?

Such ranges were given (and supported by screenshots) for the Tiger attack helicopter, for example. There is a huge difference in range between spotting something conspicuous or moving and identifying what it is, particularly if the object is heavy camouflaged with foliage. Identification by thermal sight may be impossible even at arms length if both parties use similar of near-identical tanks (such as Eastern European NATO and Ukraine still using T-72 pattern tanks).Tanks usually have their exhausts, hot barrels after firing and hot running gear after driving as outstanding warm surfaces that can be detected easily. Netting such as Saab's Barracuda or the Ukrainian pats reduce the visibility of hull and turret (which helps at long ranges against low resolution/weak zoom sensors), but there's little you can do to hide a tank from thermals after firing the main gun or driving.

No-one forces you to hide a tank in plain sight, though. It could wait behind a building or in a depression with a detached picket telling him when to leave the concealment and where to aim at. meanwhile, on the attack or during retreat "multispectral" smoke may be used to block thermal vision.

I think Hilmes and Ogorkiewicz wrote plenty about IR thermal management and camouflage issues of tanks.